chore(ci): clear the two in-repo governance false-positives (LICENSE SPDX + trusted-base) (#329)

## Summary

Two governance checks have been red on **every** PR (#322–#324) for
reasons unrelated to any diff — both are repo-level. This clears the two
that are in ephapax's control. Fixes were derived from the **exact
`standards@d135b05` check-script regexes** (fetched via raw HTTPS and
verified locally, not guessed).

### 1. `governance / Licence consistency`
Root `LICENSE` is the verbatim MPL-2.0 text with **no SPDX header**.
`check-licence-consistency.sh` does:
```sh
grep -m1 -E '^[[:space:]]*SPDX-License-Identifier:' "$lic_file"
```
then normalises the identifier and checks it matches the manifest.
**Fix:** prepend `SPDX-License-Identifier: MPL-2.0` (normalises to
`mpl-2.0`, matches `Cargo.toml` `license = "MPL-2.0"`). Verified the
grep now matches.

### 2. `governance / Trusted-base reduction policy`
`check-trusted-base.sh` flags `^[[:space:]]*(Axiom|Admitted|admit\.)`.
`formal/RegionEnvL1.v:17` is a **prose comment** — *"Axiom budget: this
file is axiom-free"* — that happens to start with "Axiom". A false
positive. **Fix:** reword to *"On the axiom budget: …"* so the line no
longer matches (verified).

Chosen over a `.trusted-base-ignore` entry deliberately: the file stays
**fully scanned**, so a genuine future axiom there is still caught — and
a `TRUSTED:`/`AXIOM:` inline annotation would be *false* (the file
really is axiom-free; that's the whole point of `RegionEnvL1.v`).

## Not fixable here
`scan / Hypatia Neurosymbolic Analysis` fails on an Elixir
`CompileError` (`real_subdirs`) **inside the `standards`/Hypatia repo**
— out of ephapax's reach. Flagging, not fixing.

## Verification
- Both fixes checked against the actual fetched regexes
(`standards@d135b05`).
- `formal/RegionEnvL1.v` still compiles under `coqc 8.18.0`
(comment-only change).
- 2 files, +3/−1.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01AGFqWzByua4dKbA7W7oVsL

---
_Generated by [Claude
Code](https://claude.ai/code/session_01AGFqWzByua4dKbA7W7oVsL)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath

LICENSE

@@ -1,3 +1,5 @@
+SPDX-License-Identifier: MPL-2.0
+
 Mozilla Public License Version 2.0
 ==================================
 

formal/RegionEnvL1.v

@@ -14,7 +14,7 @@
     [region_name -> nat] (re-entry depth per region; 0 = dead), reasoned
     up to a **pointwise-equality setoid** [renv_eq].
 
-    Axiom budget: this file is axiom-free. We use a setoid relation
+    On the axiom budget: this file is axiom-free. We use a setoid relation
     ([renv_eq]) rather than [functional_extensionality], so [Print
     Assumptions] stays clean — order-insensitivity is *definitional*
     (the carrier is a function; permutation collapses to [renv_eq]),